Here are some less mentioned FLOSS games, that are excellent quality:

Fillets-ng (2D fish sokoban)

The Dark Mod (3D stealth game, bow and sword)

Crrcsim (3D model glider flightsim, slope soaring)

Yes, it’s glorious 🤗

Cube 2: Sauerbraten

Everything that is good about 90s FPS crammed into one free download.

…and today, I also played today… but I played a lot a few years ago too.